Telescoping members and latch means therefor



Jan. 25, 1955 H. F. .1. BERNAERTS 2,700,436

TELESCOPING MEMBERS AND LATCH MEANSTHEREFOR,

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Filed Jan. 22 1951 IN VEN TOR. A e-Mela; /-?J.' fiae/vflevers TELESCOPING MEMBERS "AND LATCH. MEANS :The'present invention relates to a hydraulic liftingjack :.with a lifting column ingeneral and to a lifting member in particular, which lifting jack is preferably used fOIllft- Hing heavy-loads, e. g. aircraft.

. I Since rnost'of 'theknown'devices'of this type areoperated by means of a hydraulic system or by compressed air, the devices of this kind may cause accidents in case of faults of the pressure system working on the lifting member. Such faults are particularly dangerouswhen lifting aircraft, for, when in the lifting. position of an aircraft,

the 'lifting-member-fails and-the-aircraft drops, internal fractures-of the fuselage or the wings may -be caused. The'refore, in such lifting jacks it is of-the greatest 1mportance'thatfaults in the pressure systemnever lead toa sudden lowering of the lifting member. Ir-ior'dertoavoid the-dangerous sudden'lowering of the liftingmernber"it has been proposed'beforetoprovide a liftingmemb'er-with teethwhich cooperate-withone or more latches, the ends of which engage the'te'eth of the lifting member and, thereby, are retained in liftedposition. It was,-however, characteristic for all known structures that the latcheshad to carry'the'full load since forces parallel to the longitudinal axis of thelifting member. did "bear on the endsof the-latches engaging the teeth of the lifting member. 1t-was-,-of-course, necessary: to; provide teeth'of comparativelylarge-dimensions in order to provide sufficient-bearing surface, since the teeth alonehad to carry the heavy-load.

' It is, therefore, one object of the present invention" to providea structure comprisinga lifting memberhaving teeth: disposed-- longitudinally atits outer, face, which teeth cooperatewith theinnerend of-one or more latchesfthe axis of which latches, however, forms an acute angle with the longitudinal axis of the lifting member, inorder to provide an important pressure component perpendicularly to the surface of the lifting member, the latches, thereby, operating as clamping members, which operation decreases to a great extent the possibility of shearing of the teeth on the lifting member.

It is another object of the present invention to provide a structure comprising a lifting member having teeth longitudinally disposed on its outer face, which teeth cooperate with one or more latches, in which the latches may be unlocked by means of a cam ring, the latter including means for rendering the same operative only when the pressure system is functioning, so that an unlocking of the latches is not possible when the pressure system is out of order.

It is another object of the present invention to provide a structure comprising a lifting member having teeth longitudinally disposed on its outer face, which teeth cooperate with one or more latches, the latter being moved into inoperative lifting position by means of a cam ring to which resilient means are connected to return the cam ring automatically into the position in which the latches are in operative locking position.

It is yet another object of the present invention to provide a structure comprising a lifting member having teeth longitudinally disposed on its outer face, which teeth cooperate with one or more latches, the latter being moved into inoperative lifting position by means of a cam ring and the pressure operated lifting member may be lowered by means of a regulating valve, and in which the cam ring for lifting the latches and the handle for operation of the regulating valve are mutually locked in such manner that the cam ring can only be rotated in the closed position of the regulating valve and that the regulating valve can only be opened when the cam ring assumes the position in United States Patent Which the latches are in their" inoperative lifting position.

" With these and'other objects in view which'zwillbecome apparent in the'following detailed description, the present invention will be clearly understood in connection with .the

accompanying drawing, in'which:

Figilgives a view in elevationgpartly insection, of a lifting jack according to the invention.

" Fig.2 gives asection of one of 'the 'latchesiwith apart -of-the lifting ram.

Fig. 3. gives a transverse section taken alongthealine 3 3 of Fig. 1.

Figxgl'gives' an end VleWOH'thCfIatCh mechanism. -"Fig1'5 shows the'constru'ction of there'gulating'valve. The lifting jack consists of'a central column' with outer wall- 1, said wall being'provided with lugs. 2,.2 and3. The lugs are'connectediwith legsl4 carrying at their lower 'end footplates 5,: struts 6-being provided between .the1lugs Sand the .legs'4. The"l'egs'4.maybe connected with the lugs Z'instead of-with'the' lugs 2 in'which'ca'sethe struts 6-are.placed ina downwardposition.

T he column'comprises an "outer wall 1 andzan inner "pressure cylinder 8, the sump 9for. the" hydraulic" fluid being provided between these walls. :A hydr'aulic fi'uid, preferablyawdil; isu'sedL' "The oil'fro'm' the sump"9.may

be pumped into thechamber It of. the cylinder-Sunder thepiston 11 ofthelifting ram 12'by means of apumping system arrangedyin the bottom 13 of the colummwliich rb'ottomi l'iaycarrie's channels therein (not shown) (The'pis- *ton" 14" of the pumping-system is actuated by 'meansj'of a screw spiridle 21" with" bearing head I 22. and lock. .nuti23. :The' spindle 21.n1ay be locked with respect'to. thej ranii'by means 'of'the nut23.

In :order' to" avoid the spindle 21 from; becoming .unscrewed too far with'respectto the .insert20thelowenend 'of this spindle carries a pivoting pawl 24,;said.pawl.striking against the lower'end of the .insertf20 whenithespindle 21 is screwed upwards. -'When'the.lifting.jackis turned upside downjthe pawl: 24 turns in' theqjdirection k'ofithe arrow Xzthus enabling complete removal of. the. spiridlei2l.

"The central column consisting of.'thefcylindricalsparts 1 andS is closed at the upper. end lbymeansj OfanJan'nuIar cover. 25. containing a 'cotteri26.engaging.atslotiofthe 'lifting'ram'iZ and thus: preventing rotation ofnthe. ram.

The outersurfaceofthelifting ranf'IZ is providedwith engraved teeth 27, 28 each extending about a quarter of the periphery. These teeth 27, 28 cooperate with latches 29, 30, said latches being mounted opposite the teeth 27, 28 of the lifting ram 12 and carried by pivot pins 31 inserted into wide bores of the latches. Plate springs 32, 33 are pressed against the latches.

By a reciprocating movement of the handle 17 oil is pumped into the chamber 10 by means of the pumping system in the bottom 13 so that the lifting ram 12 is lifted. The teeth 27', 28 pass the latches 29, 30 during the lifting movement. 1

In case of a sudden decrease of the hydraulic pressure which might cause lowering of the ram, the latches 29, 30 engage the corresponding teeth 27, 28 and the weight of the load is taken up by the latches 29, 30. These latches rest with rounded parts 34 in bowl shaped recesses 35 of the column.

Unlocking of the latches is only possible when the piston ii. is again under hydraulic pressure. To this end it is necessary to lift the ram 12 for a distance of a few millimeters, so that the latches are unlocked with respect to the teeth. Now it is possible to turn the latches by means of the cam ring 36 which may be rotated by means of a handle 37 of the ring against the action of a spring 48, said spring being connected between the cam ring 36 and the cover 25. The cam ring 36 is locked against axial shifting by means of two locking plates 50, 51 connected to the cover 25 by means of screws 53.

The lifting ram 12 can now be lowered by releasing the oil from the chamber 10 into the sump 9 through the passage 38 in the bottom 13 by means of the regulating valve of Fig. 5.

The regulating valve consists of a needle valve 39 cooperating with a fixed seat in the bottom 13 of the column; this needle valve is carried by a screw spindle 40. This screw spindle engages a nut 41 which may be turned after removal of a cover 42 functioning as locking means for the adjustment of the needle valve 39. The extension 43 of the screw spindle 40 carries at its upperend a handle 44 and is pressed upwards by means of a pressure spring 45. In this way the handle 44 can take up the same position in closed position of the needle valve even after wear of needle and seat in view of the fact, that the nut 41 may be adjusted.

This is of importance in view of the mutual locking of the cam ring 36 and the spindle 43. The needle valve 39 can only be opened by turning the handle 44 in the direction of the arrow Z after the recess 46 or" the cam ring is adjusted in front of a corresponding cam 47 of the screw spindle 43, that means that after the cam ring 36 has been turned over an angle of about 90 in the direction of the arrow Y with respect to the position of Fig. 4.

In the open position of the needle valve 39 the cam ring 36 is locked. After returning the handle 44 of the needle valve from the open into the closed position as indicated in Fig. 4 the cam ring 36 is released by the part 47 and the ring 36 is returned under the action of the spring 48 in the position of Fig. 4 in which the latches 29, 30 return in the locked position.

While I have disclosed one embodiment of the present invention, it is to be understood that this embodiment is given by example only and not in a limiting sense, the scope of the invention being determined by the objects and the claims.

What I claim is:

1. In a lifting jack, the combination of a vertically disposed frame including a hollow fixed part and a longitudinal member extending throughout and past the fixed part and mounted for movement in axial direction therein, a part of the periphery of the said longitudinal member having teeth disposed longitudinally thereon, a plurality of clamping members disposed around and pivotally mounted on the said fixed part, each of said clamping members extending upwardly from its pivot point toward the said longitudinal member at an acute angle to a plane extending through the said pivot point perpendicularly to the longitudinal axis of the said movable member, when in clamping position, the inner ends of the said clamping members engaging the teeth of the said longitudinal member, to lock the latter in any position by clamping action as the result of a pressure component perpendicularly to the longitudinal axis of the longitudinal member.

2. In a lifting jack, the combination of a vertically disposed frame including a hollow fixed part and a plunger extending throughout and past the fixed part and mounted for movement in axial direction therein, a part of the periphery of the said plunger .having teeth disposed longitudinally thereon, a plurality of latches disposed around and pivotally mounted on the said fixed part, each of said latches extending upwardly from its pivot point toward the said plunger at an acute angle to a plane extending through the said pivot point perpendicularly to the longitudinal axis of the said plunger, when in latched position, the inner faces of the said latches having teeth complementary to the said teeth of the plunger, to lock the said plunger in any position by clamping action as the result of a pressure component perpendicularly to the longitudinal axis of the plunger.

3. In a lifting jack, the combination of a vertically disposed frame including a hollow fixed part and a plunger extending throughout and past the fixed part and mounted for movement in axial direction therein, a part of the periphery of the said plunger having teeth disposed longitudinally thereon, a plurality of latches disposed around and mounted on the said fixed part, each of said latches extending upwardly from its pivot point toward the said plunger at an acute angle to a plane extending through the said pivot point perpendicularly to the longitudinal axis of the said plunger, when in latched position, the said plunger having bowl-shaped recesses equal in number to that of the said latches and the latter resting in the said bowl-shaped recesses for angular movement, to lock the said plunger in any position by clamping action as the result of a pressure component which extends perpendicularly to the longitudinal axis of the said plunger and is taken up by the inner face of the said recesses of the said fixed part.

4. The lifting jack, as set forth in claim 3, which includes a cam-operated means rotatably secured to the said fixed part for maintaining the said latches in lifted inoperative position.

References Cited in the file of this patent UNITED STATES PATENTS 782,274 Reisinger Feb. 14, 1905 1,447,242 Fritz Mar. 6, 1923 1,512,837 Evenden Oct. 21, 1924 1,526,563 Powers et al Feb. 17, 1925 2,372,196 Grime Mar. 27, 1945 2,432,076 Rothery Dec. 2, 1947 2,487,792 Custer Nov. 15, 1949 2,490,284 Simart Dec. 6, 1949 2,562,493 Harris July 31, 1951 FOREIGN PATENTS 313,733 Great Britain June 20, 1929 

